The removal of dirt and debris from streets, parking lots, airport runways, factory floors, and other similar paved surfaces, through the use of various types of street cleaning vehicles, has been known for many years. Such vehicles employ either vacuum or recirculating type suctioning systems, to remove dirt and debris from a surface, lift it several feet up, and deposit it into a hopper. For the sake of brevity, clarity and simplicity, such vehicles will be generally referred to in this document as surface cleaning vehicles.
Typically, surface cleaning vehicles employing either vacuum and recirculating type systems, are used when dust control is a concern or to be able to vacuum up litter and other debris.
Conventional vacuum type systems typically employ a pair of opposed gutter brooms disposed one broom toward each of the left and right sides of the vehicle in spaced apart relation across the width of the vehicle. The gutter brooms rotate about a vertical axis to sweep dirt and debris inward to a central corridor for pickup. A vertically disposed vacuum hose having an open bottom end terminating about one foot above the surface being cleaned vacuums up the debris swept to the central corridor. Wider units have an angled window sweeping broom that feeds dirt over to the vacuum hose. The top end of the vacuum hose is in fluid communication with the hopper that receives the debris therein. The air flow in the vacuum hose is generated by a blower fan mounted on the opposite side of the hopper and exhausted to the ambient surroundings. It is well known, however, that vacuum type systems rely on the slower movement of air in the hopper to separate the debris from the air stream, and do not provide subsequent separation.
Conventional recirculating air type systems typically have a full width one-piece suction head, about five to seven feet in width, and having a flexible peripheral skirt, is driven over the surface to be cleaned, with the skirt in constant contact with the surface. A blower fan draws air from the outlet of the suction head through a large diameter vacuum hose. The dirt and debris suction up through the vacuum hose is deposited into a hopper.
In recirculating type systems, the centrifugally cleaned air is fed back into the one-piece suction head through a supply hose that is attached to an inlet disposed at an inlet end of the one-piece suction head. Turning vanes, typically comprising a set of curved plates, redirect the air blown into the inlet of the one-piece suction head through a forward pointing slot and across the width of the one-piece suction head substantially towards the other side of the suction head and slightly downwardly so as to help gather and capture dirt and debris on the surface being cleaned. The dirt and debris-laden air reaching the other end of the one-piece suction head is again drawn up through the large diameter vacuum hose.
Some conventional regenerative air type street cleaning vehicles employ a dust and debris separator with an integral skimmer hood type sealed collection chamber. The debris separator is essentially a horizontally disposed cylinder having a drop floor section at its bottom along its length, with the drop floor section defining a passage that is in fluid communication with the skimmer hood type sealed collection chamber. The air is passed through the separator in a spiral path. The drop floor section serves to strip the dust and debris from the stream of air. The stripped dust and debris pass under a pliable rubber flap and into the skimmer hood type sealed collection chamber. The separated air is drawn from the separator by the main fan, and is blown back into a suction head, where it impacts the surface being cleaned, before being drawn back up to the hopper and separator.
Recirculating air type street cleaning vehicles tend to experience cessation of the debris separating function when the sealed collection chamber becomes substantially full. In that situation, additional dust and debris cannot enter the collection chamber and thus freely swirl around in the debris separator. Accordingly, air drawn from the separator by the main fan, contains substantial amounts of dust and debris, as opposed to substantially clean air. The dust and debris in the air stream generated by the main fan impact parts of the main fan, thus potentially causing damage and significantly shortening the life of the main fan. Further, the dust and debris-laden air enters the suction head, which causes wear and damage to the suction head, and also to the various air hoses within the system, especially where the air turns corners.
It is an object of the present invention to provide a surface cleaning vehicle of the vacuum air or recirculating air type, having a separator that does not fill up during normal operation and thereby does not lose its ability to separate dust and debris on an ongoing basis, during normal operation of the surface cleaning vehicle.
It is another object of the present invention to provide a surface cleaning vehicle of the vacuum air or recirculating air type, having a separator that precludes the damage and wearing of the main fan and other components that are downstream from the dust and debris separator.